Abstract

So far, several studies have been conducted on progressive collapse of tall buildings, of which a few have been on the buildings with diagrid structures, however, in none of them the effect of the building’s plan geometry has been a concern. In this study the progressive collapse of a set of 50-story steel buildings with diagrid structures in three different plan geometries of square, rectangular, and octagonal was investigated by nonlinear static and dynamic analyses. First, the considered buildings were designed according to ASCE 7 and AISC design provisions, trying to be close as much as possible to the optimal design, based on the demand to capacity ratios. Then, five damage scenarios were considered including removal of columns and/or diagonal elements of the diagrid structure in the lowest, the 25th, and the top story of the building according to UFC provisions. Nonlinear static and dynamic analyses were conducted by Perform-3D software. Results show that robustness index, calculated by using the stiffness method would be smaller for the cases of member removal in upper stories, and that the lowest robustness index corresponds to removal of two corner columns, and bracing element connected to them, in the first and second stories. Results also show that removal of interior column in the first story leads to progressive collapse in all three plan shapes. However, yielding and ultimate load factors in building with octagonal plan are more than other two buildings, implying that this type of buildings have more resistance against progressive collapse.

中文翻译：

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基于非线性静动力分析的平面几何形状对斜肋网格结构高层建筑渐进倒塌的影响

摘要

到目前为止，已经对高层建筑的连续倒塌进行了一些研究，其中一些研究是针对斜肋构架结构的建筑物，但是，在这些研究中，建筑物平面几何形状的影响都没有受到关注。在这项研究中，通过非线性静态和动态分析研究了一组 50 层钢结构建筑的渐进倒塌情况，这些钢结构具有正方形、矩形和八角形三种不同平面几何形状的斜肋网格结构。首先，所考虑的建筑物是根据 ASCE 7 和 AISC 设计规定进行设计的，根据需求容量比，尽可能接近最优设计。然后，根据 UFC 规定，考虑了五种损坏情况，包括拆除建筑物最低层、第 25 层和顶层的斜肋构架结构的柱子和/或对角元件。通过 Perform-3D 软件进行非线性静态和动态分析。结果表明，对于上层构件拆除的情况，使用刚度法计算的稳健性指数会较小，并且最低的稳健性指数对应于拆除两个角柱以及与其连接的支撑元件，在第一层和第二层中第二个故事。结果还表明，拆除第一层的内部柱会导致所有三个平面形状逐渐倒塌。然而，八角形平面建筑的屈服系数和极限荷载系数均高于其他两种建筑，这表明该类型建筑具有更强的抗连续倒塌能力。